Soundscape Inventory Report
U.S. National Marine Sanctuary
2025-04-08
1 What is ocean sound?
Ocean sound refers to the collection of acoustic energy present in marine environments, encompassing a variety of sources, including sounds from marine animals, geophysical noise from waves, wind, rain, and human generated sounds from shipping, sonar, and offshore construction. This collection of sound at a given place and time is often called a soundscape. Monitoring ocean soundscapes provides key insight to understanding ecosystem dynamics, detecting environmental changes, and managing the impacts of noise pollution on marine organisms. Learn more about ocean sounds at Discovery of Sound in the Sea.
Why do we care? Ocean sound is critical for the survival of many marine animals because it is a primary means of communication, orientation and navigation, finding food, avoiding predators, and choosing mates. As such, human activities that produce underwater sounds have the potential to negatively impact animals by reducing their ability to hear prey, predators, and each other. U.S. national marine sanctuaries are home to many acoustically active marine animals and understanding the presence and impacts of noise is a conservation priority. Further, the occurrence and types of sounds present offer key insights on animal presence, species behaviors, human-use patterns, and changing ocean conditions.
Where are we listening? NOAA’s Office of National Marine Sanctuaries (ONMS) maintains a nationally coordinated underwater sound monitoring network, known as ONMS Sound. ONMS sound works with partners to monitor ocean sound off the US East, West, and Gulf Coasts and in the Pacific Islands region. Ocean Sound monitoring sites are placed in strategic locations within sanctuary boundaries. Data from the sound monitoring sites are available through the NOAA National Centers for Environmental Information’s Passive Acoustic Archive. Explore the ONMS sound and partner monitoring sites here.
Purpose of a soundscape inventory report This report provides regular updates on ONMS ocean sound monitoring efforts. The report includes basic summary graphics and tables to understand the soundscape and provide indicators of change. The report represents analyses that are maintained by ONMS sound. If partners are maintaining analyses, those results are also included (e.g. species detections by NMFS). We also highlight key insights from specific dedicated studies that used these data.
2 Ocean sound monitoring in Stellwagen Bank National Marine Sanctuary
The Stellwagen Bank National Marine Sanctuary is a wild ocean place near an urban world, sits east of Boston, Massachusetts between Cape Ann and Cape Cod. Historically important as a fishing ground, New England’s only national marine sanctuary now reigns as a premier whale watching destination and continues to support commercial and recreational fishing.
The history of ocean sound monitoring within SBNMS began with a focus marine mammal sounds, including the endangered North Atlantic Right Whales.Noise reduction during vessel speed reduction programs is also well studied in this region.
Current ocean sound monitoring is maintained at four sites within SBNMS. Three sites (SB01,SB02,SB03) are located more inshore, capturing more local vessel activity and sounds from nearshore species. One offshore sites (NRS09) captures patterns in migrating whales and transiting commercial vessel traffic and is part of the US Ocean Noise Reference Station Network.
Summary of ocean sound monitoring sites| Site | Primary.monitoring.purpose | Oceanographic.Setting | Depth | Seasonality | Vessel.Traffic.Setting | Latitude | Longitude | TotalDays | StartDate | Information |
|---|---|---|---|---|---|---|---|---|---|---|
| SB01 | To monitor a site that supports seasonally high abundances of Atlantic cod and is located near a region of elevated commercial vessel activity. | Continental shelf (<200m) | 50 m | Seasonal winds and baleen whales presence | near inbound TSS lane to Boston, within existing Off Race Point SMA slowing large traffic in March-April | 42.43855 | -70.5458 | 852 | 2018-11-12 | https://sanctsound.portal.axds.co/#sanctsound/sanctuary/monterey-bay/site/SB01 |
| SB02 | Part of Sanctuanry Soundscape Monitoring Project (2018-2022) | Continental shelf (<200m) | 68.3 m | Seasonal winds and baleen whales presence | NA | 42.47000 | -70.2300 | NA | 2018-11-12 | https://sanctsound.portal.axds.co/#sanctsound/sanctuary/monterey-bay/site/SB02 |
| SB03 | To monitor shallow sandy habitat situated on the bank that supports the foraging and social activities of marine mammals. | Continental shelf (<200m) | 45 m | Seasonal winds and baleen whales presence | near outbound lane to Boston and within Off Race Point SMA slowing large traffic April-May; illegal scalloping in March-April | 42.25557 | -70.1788 | 1708 | 2018-11-12 | https://sanctsound.portal.axds.co/#sanctsound/sanctuary/monterey-bay/site/SB03 |
| NRS09 | To continue long-history of monitoring trends in ocean noise, including cetacean species presense and vessel movement | Continental shelf (<200m) | 79 m | Seasonal winds and baleen whales presence | fan of traffic moving north to Canadian ports, but more distant/dispersed | 42.40000 | -70.1300 | 2701 | 2014-10-21 | https://www.pmel.noaa.gov/acoustics/noaanps-ocean-noise-reference-station-network |
3 What is the soundscape in SBNMS ?
A soundscape includes all the different sounds present at a given time and location. Soundscapes are dynamic, changing with season and annual differences in sources (wind, biologics, and human-activity). How do we visualize this information? One way is to indicate the main sound contributors on a frequency by sound level graphic, known as spectral plot. The seasonal differences are shown as the colored lines. The known sources of interest in this soundscape are indicated by vertical lines and shaded areas at specific frequency(s). Wind noise occurs within an expected range and is represented the black lines. We can track these different contributions to understand how a soundscape is changing. We can also compare across locations.
The median power spectral densities (PSD) for all hours across all years are calculated from calibrated audio data using community software tools: Triton Soundscape Metrics, MANTA, or PyPAM. Triton software calculates the one-third octave band sound pressure levels by integration of PSD levels with a 1 Hz/1 second resolution and a median was used to calculate hourly values over no less than 1,800 1-s values for that hour and converted to decibels (dB re 1 μPa). MANTA and PYPAM software calculates power spectral density (PSD) levels per minute (μPa²) within the hybrid milledecade frequency bands. PAMscapes was used to calculate the median for each hour within one-third octave bands. These values were then converted to 1-Hz resolution to match the wind model results by converting to pressure and dividing by the band width before converting back to sound spectrum levels in decibels (dB re 1 μPa/Hz).
4 What are the latest conditions in ocean sound?
Comparing annual ocean sound levels provides insights on trends in ocean sound. Using spectral plots, we can evaluate what frequencies are increasing or decreasing in recent years. For example, in the ship noise frequencies, are sound levels lower in the most recent year of monitoring? Efforts to reduce noise are underway on global to local scales, and these efforts may be be reflected in the annual data. Typically, a more focused analysis is necessary to tease apart the multiple drivers of changing ocean sound levels.
5 How often is ocean sound above wind noise?
If sound levels in a frequency of interest are above what is expected for wind noise, other sources are contributing to the soundscape. The percent of the time above wind noise tell us how often a sound contributes to the soundscape. The decibels above tell us how much sound is added.
100 Hz represents low-frequency ship noise. In many marine environments, ships are transiting the region for a variety of purposes (e.g. transporting goods, harvesting ocean resources, and carrying tourists). When these ships are transiting noise is added to the soundscape, particularly in the lower frequencies.
